This application claims the priority of German Patent Application Serial No. 100 14 904.9, filed Mar. 17, 2000, the subject matter of which is incorporated herein by reference.
The present invention relates, in general, to a pendant switch assembly, and more particularly to a pendant switch assembly for controlling various operations of a hoist to raise and lower a load-carrying member mounted to a traction member.
U.S. Pat. No. 2,791,665 discloses a pendant switch assembly for operating an overhead crane. The pendant switch assembly includes a housing for accommodating control elements in the form of switches which are actuated by an operator from outside by buttons. In response to the actuation of a button, control signals are generated by which the overhead crane is moved. The housing is connected with the overhead crane by a cable. Running along the cable is a separate electric cable by which the control signals are conducted to the overhead crane.
European Pat. No. EP 592,795 discloses a pendant switch assembly which includes a housing for accommodating control elements which are actuated by push buttons. The housing has an upper end which is connected via an electric cable, provided with a central strain relief cable, to a hoist and its control mechanism. The upper housing portion has a plug for connection with the cable via a quick-action coupling. This housing portion is also provided for grabbing and maneuvering the pendant switch assembly.
A problem of conventional pendant switch assemblies resides in the fact that the operator is greatly restricted by the length of the connecting cable in his/her freedom of movement relative to the hoist.
It would therefore be desirable and advantageous to provide an improved pendant switch assembly to obviate prior art shortcomings.
According to one aspect of the present invention, a pendant switch assembly for controlling a hoist, includes a housing, a transmitter mounted to the housing for wireless transmission of control signals to a receiver mounted remotely with respect to the housing and operatively connected to a power controller of a drive of the hoist, a plurality of control elements arranged in the housing, a plurality of actuators operatively connected to the control elements in one-to-one correspondence and acted upon from outside to operate the control elements for delivering control signals for the power controller, a traction member secured to the hoist and guided downwards, a receptacle secured to a lower end of the traction member, with the housing and the receptacle having complementary locking elements so that the housing can be securely pushed into the receptacle for attachment, and pulled out again for detachment, and a power source for supplying electric energy to the control elements and the transmitter.
The present invention resolves prior art problems by configuring the housing and the receptacle in such a manner that the housing can be plugged into the receptacle for attachment, and withdrawn again for detachment, and by providing a wireless transmission of control signals through provision of a transmitter, fitted within and/or mounted at the housing, and a receiver situated at a location remote to the housing, whereby the power supply for the control elements and the transmitter is accommodated in the housing. As a consequence of the wireless transmission of the control signals and the detachable securement between the housing and the receptacle, the pendant switch assembly can easily be separated from the receptacle so that the operator is able to control the hoist irrespective of the length of the traction member.
According to another feature of the present invention, a handle is mounted to the receptacle, for maneuvering the hoist in a direction transversely to a lifting direction. Of course, the receptacle itself may be configured as handle.
According to another feature of the present invention, the receptacle and the housing may have as complementary locking elements cooperating protrusions and indentations. For example, the housing may have indentations for engagement by complementary protrusions on the receptacle, or the housing may have protrusions for engagement in complementary indentations of the receptacle.